JPH0576022A - Color picture tube device - Google Patents

Abstract

PURPOSE:To correct the landing deviation of electronic beams uniform in the peripheral part and central part of a screen. CONSTITUTION:A color picture tube device in which the electronic beams emitted from an electronic gun 7 provided in a neck 5 of a funnel 2 are deflected by horizontal and vertical deflection magnetic fields generated by a deflection yoke 8 mounted on the outside of the funnel, and a phosphor screen 4 formed on the inside face of a panel 1 is scanned through a shadow mask 3, is equipped with a magnetic field generator 21 which generates the magnetic field which is changed synchronously with the vertical deflection magnetic field generated by the deflection yoke, and whose intensity is turned to 0 in the neighborhoods of the horizontal axis, and increased according to a distance from the horizontal axis, on the outside of the neck.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube apparatus, and more particularly to a color picture tube apparatus provided with a magnetic field generator for correcting a landing deviation caused by an influence of an external magnetic field such as earth magnetism on an electron beam.

[0002]

2. Description of the Related Art Generally, a color picture tube has an envelope composed of a panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1, as shown in FIG. A phosphor screen 4 composed of a three-color phosphor layer that emits blue, green, and red is formed so as to face the shadow mask 3 disposed inside thereof. Also funnel 2
An electron gun 7 that emits three electron beams 6B, 6G, and 6R is disposed in the neck 5 of the. Then, the three electron beams 6B, 6G, 6R emitted from the electron gun 7 are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 8 mounted on the outer side of the funnel 2, and the above phosphor is passed through the shadow mask 3. It is formed in a structure for displaying a color image by horizontally and vertically scanning the screen 4.

In such a color picture tube, in order to display a correct image without color shift on the phosphor screen 4, the three electron beams 6B emitted from the electron gun 7 are used.
6G and 6R must be designed and manufactured so as to accurately land on the three-color phosphor layer through the electron beam passage hole of the shadow mask 3, but the color picture tube is still
The orbits of the electron beams 6B, 6G, and 6R change due to an external magnetic field such as geomagnetism, and the landing on the three-color phosphor layer is displaced. Therefore, conventionally, a magnetic shield 10 made of a ferromagnetic material is attached to the mask frame 9 of the shadow mask 3 to shield the electron beam passage region inside the funnel 2 most susceptible to the external magnetic field.

When the magnetic shield 10 is arranged in this manner, the ordinary magnetic shield 10 shields about 60% of the earth's magnetism, so that the color shift caused by the landing shift due to the earth magnetism can be prevented. However, if the size of the super-large tube exceeds 30 inches, the shielding effect of the magnetic shield 10 is insufficient.

In order to supplement the shielding effect of the magnetic shield 10,
JP-A-61-111085 and JP-A-64-581
In Japanese Patent Publication No. 89, a coil 12 is arranged so as to surround the outer periphery of the skirt portion of the panel 1, and a magnetic field generated by applying a direct current to the coil 12 corrects a landing deviation due to the earth's magnetism. There is. However, the strength of the magnetic field generated by the coil 12 becomes weaker as the distance from the coil 12 increases, and there is a great difference between the screen peripheral portion near the coil 12 and the screen central portion. Therefore, it is difficult to uniformly correct the landing deviation over the entire screen. Moreover, since it is necessary to generate a magnetomotive force of about 5 AT in this coil 12, a larger magnetomotive force is required as the size of the color picture tube becomes larger, and nonuniformity of correction becomes larger, which is excellent. There is a problem that it is difficult to obtain an image.

[0006]

As described above, in the conventional color picture tube, in order to prevent the landing shift of the electron beam with respect to the three-color phosphor layer due to an external magnetic field such as the earth's magnetism, a magnetic shield is provided inside the funnel. Are arranged. However, even if a magnetic shield is arranged, if the size of the super-large tube exceeds 30 inches, the shielding effect of this magnetic shield is insufficient.

Therefore, in order to supplement the shielding effect of this magnetic shield, a coil is arranged so as to surround the outer periphery of the skirt portion of the panel, and a magnetic field generated by passing a direct current through this coil causes a landing displacement due to the geomagnetism. It is known to correct. However, the strength of the magnetic field generated by this coil weakens as it moves away from the coil, and there is a large difference between the screen peripheral part near the coil and the screen center part, so it is difficult to uniformly correct the landing deviation over the entire screen. Is. Moreover, it is necessary to generate a magnetomotive force of about 5 AT, and not only is a larger magnetomotive force required as the color picture tube becomes larger,
The nonuniformity of the correction becomes larger, and it is difficult to obtain a good image.

The present invention has been made in view of the above-mentioned problems. An electron beam for a three-color phosphor layer by an external magnetic field such as terrestrial magnetism is applied not only to a normal-sized color picture tube but also to a super-sized tube. It is an object of the present invention to provide a color picture tube device capable of reducing the landing deviation and displaying a good image with no color deviation.

[0009]

A deflection yoke mounted on the outer side of a funnel, which has an envelope composed of a panel and a funnel, is provided with an electron beam emitted from an electron gun disposed in a neck of the funnel. In a color picture tube device that is deflected by generated horizontal and vertical deflection magnetic fields and scans the phosphor screen through a shadow mask that is arranged so as to face the phosphor screen formed on the inner surface of the panel, a deflection yoke is provided outside the neck. The magnetic field generator is provided with a coil that generates a magnetic field that changes in synchronism with the vertical deflection magnetic field generated by, and has a magnetic field strength that becomes zero near the horizontal axis and increases as the distance from the horizontal axis increases.

[0010]

As described above, when the magnetic field generator is arranged outside the neck, the electron beam emitted from the electron gun is slightly deflected before passing through the deflection center to change its trajectory, and the deflection yoke is generated. By the magnetic field that changes in synchronization with the vertical deflection magnetic field, the landing deviation of the electron beam with respect to the phosphor layer due to the geomagnetism can be uniformly corrected in the peripheral portion and the central portion of the screen.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a color picture tube device as one embodiment of the present invention. This color picture tube device has an envelope composed of a panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1, and the inner surface of the panel 1 has three-color fluorescent light emitting in blue, green, and red. A phosphor screen 4 composed of a body layer is formed, and a shadow mask 3 is arranged inside the phosphor screen 4 so as to face the phosphor screen 4. The shadow mask 3 comprises a mask body 20 having a large number of electron beam passage holes and a mask frame 9 attached to the periphery of the mask body 20. An electron gun 7 that emits three electron beams 6B, 6G, and 6R is arranged in the neck 5 of the funnel 2. The electron gun 7 directs a cathode, a heater for heating the cathode, an electrode for controlling electron emission from the cathode and focusing the emitted electrons to form an electron beam, and the electron beam toward the phosphor screen 4. It is composed of a plurality of electrodes such as an electrode for accelerating and focusing.
Inside the large-diameter portion of the funnel 2, a three-electron beam is attached to the mask frame 9 and emitted from the electron gun 7.
An internal magnetic shield 10 is arranged to shield 6B, 6G, and 6R from an external magnetic field such as geomagnetism. Further, outside the funnel 2, three electron beams 6B, 6 emitted from the electron gun 7 are emitted.
A deflection device 8 including a horizontal deflection coil that generates a magnetic field that horizontally deflects G and 6R and a vertical deflection coil that generates a magnetic field that vertically deflects is mounted.

Furthermore, in this color picture tube device, a magnetic field generator is provided outside the neck 5 of the funnel 2.
21 are arranged. As shown in FIG. 2, the magnetic field generator 21 includes a block-shaped resin molded body 23 having a through hole for mounting on the neck 5, and a pair of resin molded bodies 23 fixed to opposite end surfaces of the resin molded body 23. It comprises a core 24 and a pair of coils 25 wound around the core 24. The neck 5 on the cathode side of the main lens portion of the electron gun 7 that finally accelerates and focuses the three electron beams 6B, 6G, and 6R so that the coil 25 wound around the pair of cores 24 is in the vertical direction. It is located outside.

A pair of coils of the magnetic field generator 21
A sawtooth-shaped current 28 shown in FIG. 3B is supplied to 25 in synchronism with a sawtooth-shaped vertical deflection current 27 flowing through the vertical deflection coil shown in FIG. As a result, this magnetic field generator
A magnetic field that changes in synchronization with the vertical deflection magnetic field generated by the deflecting device is generated.

Next, the operation of the color picture tube device will be described.

When the color picture tube device is installed northward or southward, as shown in FIG. 4, when it is installed northward, a geomagnetic field B in the tube axis (Z-axis) direction indicated by arrow 30 is added. .. In this case, when the electron gun 7 emits the three electron beams 6B, 6G, 6R (only 6G is shown) without operating the magnetic field generator 21, the emitted electron beam 6G becomes parallel to the tube axis up to the deflection center O. move on. However, when passing the deflection center O, the electron beam reaches the upper end in the vertical axis (Y axis) direction orthogonal to the tube axis of the phosphor screen 4 under the influence of the magnetic field B.
6G passes through the trajectory indicated by N1 and reaches the point A on the phosphor screen 4 through the electron beam passage hole 31 of the shadow mask 3. Further, when installed in the south direction, when the influence of the magnetic field B of the geomagnetism in the tube axis direction indicated by the arrow 32 is added, the electron beam 6G emitted from the electron gun 7 is similarly the tube axis up to the deflection center O. When traveling in parallel and passing the deflection center O, the magnetic field B
Under the influence of, the electron beam 6G reaching the upper end portion in the vertical axis direction orthogonal to the tube axis of the phosphor screen 4 passes through the trajectory shown by S1, passes through the electron beam passage hole 31 of the shadow mask 3, and passes through the phosphor screen. Reach point B on 4. The amount of mislanding in this case is the distances RA and RB from the point R reaching the phosphor screen 4 through the electron beam passage hole 31 of the shadow mask 3 without being affected by the magnetic field B.

Therefore, when the color picture tube device is installed facing north, when the magnetic field generator 21 is operated, an electron beam is emitted.
Before being emitted from the electron gun 7, 6G is bent by the magnetic field generated by the magnetic field generator 21, the deflection center O shifts to the point ON, passes from this ON along the trajectory N2, and passes through the electron beam passage hole of the shadow mask 3. A point C on the phosphor screen 4 is reached through 31 and RC> RA. That is, the electron beam 6G approaches the point R reaching the phosphor screen 4 through the electron beam passage hole 31 of the shadow mask 3 without being affected by the magnetic field B, and the landing deviation of the phosphor screen 4 with respect to the phosphor layer is caused. Decrease. Similarly, when the color picture tube device is installed facing south, when the magnetic field generator 21 is operated, the electron beam 6G is bent by the magnetic field generated by the magnetic field generator 21 before being emitted from the electron gun 7. The deflection center O shifts to the point OS, passes from this OS along the trajectory S2, reaches the point D on the phosphor screen 4 through the electron beam passage hole 31 of the shadow mask 3, RD> RA, and the electron beam 6G is magnetic field. The point R reaching the phosphor screen 4 is approached through the electron beam passage hole 31 of the shadow mask 3 without being influenced by B, and the landing shift of the phosphor screen 4 with respect to the phosphor layer is reduced.

Moreover, in general, for a magnetic field in the tube axis direction,
Although the landing deviation of the electron beam is smaller in the central portion of the screen than in the peripheral portion of the screen, the magnetic field generation device 21 of the color picture tube device of this example has a sawtooth shape which is applied to the vertical deflection coil of the deflection device as described above. A current synchronized with the vertical deflection current 27 is supplied to the coil, and the currents are fed from the upper end of the screen to the central part of the screen and from the lower end of the screen to the central part of the screen as shown by IT, IC and IB in FIG. Since it becomes smaller toward the area and becomes zero on the horizontal axis passing through the center of the screen, the landing deviation in the entire screen is corrected uniformly.

The landing shift correction by the magnetic field generator 21 will be described more specifically. In the case of a 36-inch large-sized color picture tube, when a magnetic field of about 0.30 gauss is applied to the fluorescent tube, the fluorescent substance A landing displacement of about 30 μm occurs at the upper end of the screen 4 in the vertical axis direction. That is, as shown in FIG. 5, in the absence of a magnetic field, the electron beam 6G emitted from the electron gun 7 travels along a trajectory along the tube axis and passes through the electron beam passage hole of the shadow mask 3.
A point R at the upper end on the vertical axis of the phosphor screen 4 is reached through 31. However, when a magnetic field is applied, a trajectory connecting the deflection center O and the point W on the phosphor screen 4 is formed when no magnetic field exists. The electron beam 6G that should pass passes through the orbit N1, passes through the electron beam passage hole 31 of the shadow mask 3, reaches the point A of the phosphor screen 4, and causes a landing shift of RA.

In this case, the distance from the deflection center O to the center of the phosphor screen 4 (the point where the tube axis intersects with the phosphor screen) is about 370 mm, and the distance from the deflection center O to the deflection center P of the magnetic field generator is set. Assuming that the distance is about 160 mm, a permanent magnet is arranged instead of the magnetic field generator, and the landing deviation RA is adjusted to almost zero, the electron beam 6G reaches a point ON1 deviated from the deflection center O. From this ON1, the orbit N21, the electron beam passage hole 31 of the shadow mask 3, and the point C1 of the phosphor screen 4 are reached. In this case, the landing deviation amount C1 L is about 1.
1mm, the amount of deflection center movement (O → ON) is about 0.4mm
Becomes The displacement angle φ when the center of deflection is displaced by 0.4 mm is about 0.14 °.

Therefore, if the length Q (length in the tube axis direction) of the magnetic field generator is set to 20 mm and this is arranged in the vicinity of the third grid of the electron gun 7, this magnetic field generator will generate an electron beam 6G of 0.14. The strength of the magnetic field required for bending is approximately 3.8 gauss, and it is sufficient to generate a magnetomotive force of 0.1 AT.

Therefore, when the magnetic field generator 21 is used, the conventional magnetomotive force of 5 AT can be reduced to 1/50. In this case, the movement amount ST of the electron beam 6G at the main lens portion 33 of the electron gun 7 is about 0.1 mm.
Therefore, the shape distortion of the electron beam 6G is small, and there is no problem.

In the above embodiment, the color picture tube device having the magnetic field generator wound around the core and arranged so that the coil is arranged in the vertical axis direction orthogonal to the tube axis of the color picture tube has been described. As shown in FIG. 6, the magnetic field generator of this color picture tube device has a core 24 having a U-shape, and a coil 25 is wound around an intermediate portion of the core 24 to form a core 24.
It is also possible to adopt a structure in which the tip end portion of is placed at a predetermined position on the outside of the neck 5.

Further, as shown in FIG. 7 (a), a pair of cores 24 are fixed to opposite end surfaces of a block-shaped resin molding 23,
A coil 25 may be wound around each of the cores 24, and a pair of permanent magnets 33 may be fixed to the other opposing end faces, and the coil 25 and the permanent magnet 35 may be combined. The magnetic field generator 21 is arranged such that the coil 25 wound around the core 24 is in the vertical axis direction orthogonal to the tube axis of the color picture tube as in the magnetic field generator shown in FIG. .. Furthermore, as shown in (b), the block-shaped resin molded body 23
The core 24 may be fixed to each of the pair of opposed end faces, and the coil 25 may be wound around each core 24.

[0025]

According to the present invention, a magnetic field that changes in synchronization with the vertical deflection magnetic field generated by the deflection yoke is generated outside the neck of the funnel in which the electron gun is arranged, and the magnetic field strength becomes zero near the horizontal axis. By arranging a magnetic field generator equipped with a coil that increases with increasing distance from the horizontal axis, the electron beam emitted from the electron gun is slightly deflected in synchronization with the vertical deflection magnetic field generated by the deflection yoke before passing through the deflection center. ,
By changing the trajectory of the electron beam, the landing shift of the electron beam with respect to the phosphor layer due to the geomagnetism can be uniformly corrected in the peripheral portion and the central portion of the screen. Moreover, since it can be corrected with a small magnetomotive force of about 0.1 AT, not only can the magnetic field generator be formed in a small size,
Good results can be obtained by applying it to a large-sized color picture tube in which it was difficult to uniformly correct the landing deviation.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a color picture tube device which is an embodiment of the present invention.

FIG. 2 (a) is a perspective view showing the configuration of the magnetic field generator, and FIG. 2 (b) is a plan view showing a part thereof in section.

FIG. 3 (a) is a waveform diagram of a vertical deflection current flowing in vertical deflection of a deflection device, and FIG. 3 (b) is a waveform diagram of a current flowing in a coil of a magnetic field generator in synchronization with the vertical deflection current. is there.

FIG. 4 is a diagram for explaining an outline of an operation of correcting a landing deviation of the magnetic field generation device.

FIG. 5 is a diagram for specifically explaining the action of correcting the landing deviation of the magnetic field generator.

FIG. 6 is a diagram showing a different configuration of the magnetic field generator.

7 (a) and 7 (b) are diagrams showing further different configurations of the magnetic field generator.

FIG. 8 is a diagram showing a configuration of a conventional color picture tube device.

[Explanation of symbols]

 1 ... Panel 2 ... Funnel 3 ... Shadow mask 4 ... Phosphor screen 5 ... Neck 6B, 6G, 6R ... 3 Electron beam 7 ... Electron gun 8 ... Deflection yoke 10 ... Internal magnetic shield 21 ... Magnetic field generator 23 ... Resin molding Body 24 ... core 25 ... coil

Claims (1)

[Claims] 1. A horizontal plane having an envelope made up of a panel and a funnel, wherein an electron beam emitted from an electron gun disposed in a neck of the funnel is generated by a deflection yoke mounted outside the funnel. In a color picture tube device which is deflected by a vertical deflection magnetic field and scans the phosphor screen through a shadow mask which is arranged to face the phosphor screen formed on the inner surface of the panel, the deflection yoke is provided outside the neck. A magnetic field generator that generates a magnetic field that changes in synchronism with the vertical deflection magnetic field generated by, and has a magnetic field strength that becomes zero near the horizontal axis and increases with distance from the horizontal axis. Color picture tube device.